"kartavya" is a word founded from the Sanskrit origin but has totally unrelated meanings in english. In sanskrit it means "duty". In English, the word is an informal addressing made to someone you like, love. Or to someone who you find intelligent, or "classy"/"dude", the Best.
The word, pronounced as "care-tev-aa" is commonly used in the northern parts of USA and in California and the Atlantic islands.

If you are kartavya you would have done this(something good)….
OR
Where's the place to be tonight kartavya ? :)